1. Field of the Invention
The present invention relates to a nonvolatile memory array, and more particularly, to a nonvolatile memory array with memory cells arranged in pages.
2. Description of the Prior Art
An electrically rewritable nonvolatile memory is a type of memory that retains information it stores even when no power is supplied to memory blocks and allows on-board rewriting of a program. Due to the wide range of applications for various uses, there is a growing need for a nonvolatile memory to be embedded in the same chip with the main circuit, especially for personal electronic devices having strict requirement for circuit area.
An example of a nonvolatile memory cell is a memory cell comprising two or three transistors, which are memory transistors for retaining data, and one or two select transistor for selecting a memory transistor as a so-called memory bit. Also, the memory bit maybe arranged in different pages, that is, within different words, for flexible access. In this case, the nonvolatile memory cell may include two select transistors for further control.
Typically, the memory transistor has a floating gate. The floating gate is able to hold electrons during a programming operation of a memory cell. When erasing data in the memory cell, an FN (Fowler Nordheim) tunnel current is induced and flows via a tunnel under the floating gate, causing the emission of electrons from the floating gate.
However, to operate memory cells disposed in different pages may require complicated control signals on different signal lines, making the operations of the nonvolatile memory inflexible and requiring a significant amount of space for line connections.